This invention relates to a solid-state light-emitting device and particularly concerns a semiconductor laser.
In semiconductor laser devices, as a result of employment of a double heterostructure, lasing at room temperature becomes possible and practical uses of the semiconductor laser device becomes attractive. Double heterostructure semiconductor lasers of an early stage were announced by M. B. Panish et al. in pp 326-327 of Applied Physics Letters, volume 16, number 8 published on Apr. 15, 1970. The device announced in the abovementioned publication has the structure that an n-type Ga.sub.1-x Al.sub.x Ae region, a p-type GaAs region and a p-type Ga.sub.1-x Al.sub.x As region are formed sequentially on a substrate of n-type GaAs crystal. In the abovementioned device, current is made to flow from the p-type Ga.sub.1-x Al.sub.x As region to the n-type GaAs substrate, and carriers as well as lidht are confined in the GaAs active region, which is a thin region disposed perpendicular to the direction of the current.
Subsequently, as an improved device capable of confining the light in a limited narrow part of an active region, the so-called stripe-type semiconductor laser has been developed. In the stripe-type semiconductor laser, it becomes possible to decrease considerably the threshold current for lasing thereby enabling low current operation. This becomes possible by confining carrier and light within a narrow stripe region. However, even in such a stripe-type laser, dispersion of current in the active region cannot be ignored, and the threshold current is not prominently reduced even when the width of the stripe region is sufficiently narrowed. Moreover, in such a stripe-type laser, on account of the insulation film, of, for instance, SiO.sub.2 or SI.sub.3 N.sub.4 disposed on the surface of the semiconductor wafer except on the surface of the stripe shaped electrode contact, a considerable strain caused by difference of thermal expansion coefficient is produced at the interface between the semiconductor and the insulation film, and the effect of the strain reaches the active region resulting in deterioration of the lasing characteristic, hence shortening the life of the device.